Lever press



LEVER PRESS Filed Dec. 23. 1964 Sheets-Sheet l INVENTOR /-T mux BY J ATTORNEY United States Patent 3,342,059 LEVER PRESS Friedrich-Gunther Laux, Konigsweg 301, Berlin 39, Germany Filed Dec. 23, 1964, Ser. No. 420,827 4 Claims. (Cl. 72410) ABSTRACT OF THE DISCLOSURE A hand-operated compression tool in which a cam, driven by a ratchet and pawl linkage, is employed to displace a compression die toward a mating die. The driving pawl for the ratchet is mounted to a movable handle which is in turn mounted on an eccentric pivot. Movement of the handle engages the pawl against the ratchet wheel, thereby causing step-by-step rotation of the cam which drives the compression jaw. A mechanical advantage ratio on the order of 1:600 may be obtained in this device. In order to permit rapid positioning of the cam it is provided with a handle by which it may be rotated directly, after the driving pawl has been disengaged by swinging the movable handle to an extreme position.

The present invention relates to a lever press and, more specifically to a lever press for joining electrical cables by means of press fitted connecting bushings. As it is well known in the art, the two cables to be joined are pushed in overyling relation into a suitably formed bushing, whereupon notches are pressed into the bushing by means of a tongs-like tool, which notches effect their action up to the upper lead of a cable, which latter is composed of a plurality of individual leads. If a cable is dissected for demonstration purposes, it may be seen, that the cable assumes a wave-like configuration, this configuration being caused by the action of the notches. Thereby is attained, that the cable joint is able to stand at its joint the considerable traction forces, which may arise at this position, as well as the additional forces, which may be caused by vibrations. Further the said joint must be able to stand variations of temperature without separation of the joint and the excess-current strengthi.e. the necessary conductivity at the transition points between the two cablesmust be assured without there arising at the cable joint an inadmissible high temperature, as it may be caused by an excessively high value of the electrical contact resistance. In this connection, it is to be noted, that the oxydation of the metal surfaces at the joint is of considerable importance, because such oxydation tends to increase the contact resistance. Decreasing the contact resistance is of especial importance in the case of shortcircuits in the mains, in which case high values of current in the cable also have an effect on the cable joint. Out of this reason the conductance at the joint of the cable ends must not be lower than the conductance in the remaining cross section of the cable. By the device according the present invention all the above mentioned requirements are met. The device consist of a hand-operated press, in which a very transmission ratio of about 1:600 is attained by transmitting power from two hand levers via two eccentrics, a pawl and a ratchet wheel.

For the purpose of attaing cable joints showing high values of conductance and tensile strength, the tongs according to the invention use special press inserts, in which the edges turned towards each other assume the shape of an M.

Particularities of the present invention are now described with reference to the attached drawing, in which shows:

. 3,342,059 Patented Sept. 19, 1967 FIGURE 1 the basic arrangement of a cable joint with the hand-actuated lever press in place;

FIGURE 2 a longitudinal section of the lines IL-II of FIG. 3;

FIGURE 3 another cross section, displaced by degrees and along line III-III of F G. 2;

FIGURE 4 a plan view of the two press shoes as detached from the press; and

FIGURE 5 a cross section of one of the press shoes along line VV of FIG. 4.

According to the present invention the hand-actuated lever press is composed of two side members 1, 2 presenting each on the faces turned towards each other a longitudinal groove 3, 4 respectively. Into the said grooves 3, 4 the press insert 7 is slid, the latter consisting of the two press shoes 5, 6.

This sliding-in being efiected, above the upper edge 8 of the topmost press shoe 5 a retaining bolt 9 is passed through holes 10, 11 in the side members of the press. The retaining bolt presents at one of his ends a knurled head 12 and in addition to this two annular grooves 13, 14, selectively adapted to accept a retaining ring 15, the latter being mounted in an annular housing 16 on the left-hand side member 1 and assuring, that retaining bolt goes into snap-engagement at the open and closed position respectively.

Below the lower edge 17 of the bottom press shoe 6, there is mounted a press bolt 18 in the two grooves 3, 4 in free slidable relation in the vertical directions, by engaging by means of the square-head stud 19 into the longitudinal grooves 3, 4. The press bolt. 18 is surrounded for about three-quarters of its circumference by bolt slots provided in respectively each of two eccentric discs 20, as may be seen best from FIG. 2. Each of the said eccentric discs 20 rests upon an eccentric .21 of an eccentric shaft 22, the latter being mounted by means of the studs 23, 24 in bores 25, 26 provided in the side menbers 1, 2. Between the two eccentrics 21, arranged in spaced relation to each other, there is provided a fixedly mounted ratchet wheel 27, which is engaged from below by a pawl 29 under the action of a compression spring 31 upon the pawl lever 30, the pawl being pivotably mounted by means of a stud 28. The two side members 1 and 2 are box-like surrounded at their central and lower portions by side walls 32.

At the lower portion, there is provided a hand-lever mounting 33, the latter being composed of a bearing bushing 34, secured to the side members 1, 2 by welding, over which is slided a tube handle 35, which in turn is secured by a rivet 36. In bores 37, 38 there are from the interior pushed in caps 39, 40 until the latter engage flanges 41, 42 provided on each of the said caps, the latter serving as bearings for each of two pawl eccentric studs 43, 44 respectively, which in turn are mounted on a bushing 45 of the second lever 46.

Upon the two eccentric studs 43, 44, there rests an indexing pawl 47 in a bolt 66, which pawl engages from below by means of its indexing tooth 48 the teeth of the ratchet wheel 27. In order to assure a reliable engagement, there is mounted in the hollow interior of handle 46 a tension spring 49, the latter engaging by means of its spring hook 50 the bore 51 of the indexing pawl 47.

The two side members 1 and 2 are secured together by screw bolts 52, of which FIG. 2 shows only the two upper ones and one of the lower ones, the bolt 28 serving simultaneously as a mounting for pawl 29.

The press shoes 5, 6 are at their side edges reduced in section by providing shoulders 53 for the purpose to be adapted to be guided by the longitudinal grooves 3, 4. The edges 54 of the press shoes turned towards each other, have the shape of an M, thereby providing an obtusethe press along angled projection 55, serving the purpose, to press V- shaped notches into the bushing of the cable joint, when the press shoes are pressed together. This action assures an extremely intimate connection between the cable ends and the bushing, those leads of the cable situated near the wall of the bushing being deformed to the greatest extent, thereby assuring not only good contact and a high value of the transition conductance together with a low value of the transition resistance, but also a mechanically good connection, which tends to prevent to a great extent the separation of the joint.

In order not to loose the two press shoes and to automatically separate the shoes when opening the press, the said shoes are connected together by a wire spring 56, the latter being formed near to the shoe helically to provide an almost complete turn 57 and being secured by means of its dual-angled end 58 in a bore of the respective shoe 59.

The functioning of this arrangement is as follows: After the two cables 60 have been pushed into the cable bushing 61, next the retaining bolt 29 is pulled out of the side members 1, 2 until retaining ring 15 comes into snap engagement with the outer annular groove 14 of the bolt. Next, the press insert is removed from the grooves 3, 4 and positioned around the cable bushing 61, whereupon the press insert together with the cable bushing and the cables 60 are slided from above into the grooves 3, 4 of the lever press. Then the retaining bolt is pushed by means of the knurled disc 12 to the interior, whereby the annular groove 14 is freed of the retaining ring 15, until the outer end of the retaining bolt enters the bore 11 of the righthand side member 2 and the retaining ring 15 makes snap-engagement with the inner annular groove 13. Now, the two handles 62, 63 of the lever press are gripped and alternatively motions toward each other (arrows 64) and from each other (arrows 65) respectively are effected. By doing so, the eccentric bolt 66 is caused to act via the eccentric studs 43, 44 upon the indexing pawl 48 and the ratchet wheel 27 is rotated through the pivoting motion of the tube handle 67 in the direction of arrow 64 in the direction of arrow 68, whereupon the eccentric discs 20 are moved stepwise under the action of eccentric 21 to the top, so that bolt 18 causes the lower press shoe to move to the top and the cable bushing 61 is engaged between the press shoes, whereupon V-notches are pressed by means of the projections 55 into the cable bushing 61.

In order to loosen the press shoes, the left-hand tube handle 67 is pivoted in the direction of arrow 65 to the top as far as possible, whereupon indexing pawl 48 is completely freed from the teeth of ratchet wheel 27. In order to maintain tube handle 67 in this position, spring washers are fitted in the mounting of tube handle 67 in such a manner, that upon tightening the side-member screws 52, 28 a friction-type engagement is efiected between the mounting of tube handle 67 and the side members 1, 2. Next, by exerting pressure upon lever 30 the pawl 29 is also disengaged from the teeth of ratchet 27, and now, by means of the knurled handle 70, being mounted at the shaft 23 of the eccentrics 21, the ratchet wheel 27 may be rotated in such a manner, that eccentric disc 20 is caused to move into the bottom position. Thereby the lower press shoe is released and pushed by means of spring 56 downward, so that the press insert is loosened and after removing of retaining bolt 9 the joined cables may be removed from the press.

This loosening of the press shoes may be effected in the manner just described also during the operation of the press, this being necessary especially in the case of the press operator having initiated a incorrect pressing cycle.

I claim:

1. A lever-actuated compression tool capable of producing a mechanical advantage on the order of 1:600 for comprising articles between a pair of dies, comprising:

a first hand lever;

a compression die coupled to said first hand lever for slidable movement relative thereto;

an eccentric cam rotatable mounted to said first hand lever in position to displace said compression die from a given position as said cam is rotated;

a ratchet wheel coupled to said eccentric cam in substantially fixed relation therewith about a common axis;

a second hand lever coupled to said first hand lever by means of an eccentric pivot;

a pawl member mounted to said second hand lever in position to operatively engage and rotate said ratchet wheel as said second lever is pivoted from one position to another;

whereby movement of said second hand lever about said eccentric pivot advances said pawl against said ratchet wheel which in turn rotates said eccentric cam and causes said compression die to be moved slidably relative to said first hand lever, toward a mating die.

2. A compression tool in accordance with claim 1 further including a pressure-transmitting bolt slidably coupled to said first lever and interposed between said eccentric cam and said compression die for transmitting force from said cam to said compression die by movement transverse to its own axis in response to rotation of said cam.

3. A compression tool in accordance with claim 2 further including a second eccentric cam, wherein said eccentric cam and said second eccentric cam are mounted on a common axis in fixed, parallel and aligned relationship on opposite sides of said ratchet wheel and each eccentric cam is fixedly coupled to said wheel.

4. A compression tool in accordance with claim 1 including a mating compression die coupled to said first hand lever in substantially fixed relationship, wherein said compression die and said fixed die include a pair of opposed faces of substantially M-shape cross section such that obtuse angled projections are formed which may be compressed into an article positioned between the dies.

References Cited UNITED STATES PATENTS 6/1957 Hensgen et a1. 724l0 10/1966 Erdmann 72410 

1. A LEVER-ACTUATED COMPRESSION TOOL CAPABLE OF PRODUCING A MECHANICAL ADVANTAGE ON THE ORDER OF 1:600 FOR COMPRISING ARTICLES BETWEEN A PAIR OF DIES, COMPRISING: A FIRST HAND LEVER; A COMPRESSION DIE COUPLED TO SAID FIRST HAND LEVER FOR SLIDABLE MOVEMENT RELATIVE THERETO; AN ECCENTRIC CAM ROTATABLE MOUNTED TO SAID COMPRESSION DIE LEVER IN POSITION TO DISPLACE SAID COMPRESSION DIE FROM A GIVEN POSITION AS SAID CAM IS ROTATED; A RATCHET WHEEL COUPLED TO SAID ECCENTRIC CAM IS SUBSTANTIALLY FIXED RELATION THEREWITH ABOUT A COMMON AXIS; A SECOND HAND LEVER COUPLED TO SAID FIRST HAND LEVER BY MEANS OF AN ECCENTRIC PIVOT; A PAWL MEMBER MOUNTED TO SAID SECOND HAND LEVER IN POSITION TO OPERATIVELY ENGAGE AND ROTATE SAID RATCHET WHEEL AS SAID SECOND LEVER IS PIVOTED FROM ONE POSITION TO ANOTHER; WHEREBY MOVEMENT OF SAID SECOND HAND LEVER ABOUT SAID ECCENTRIC PIVOT ADVANCES SAID PAWL AGAINST SAID RATCHET WHEEL WHICH IN TURN ROTATES SAID ECCENTRIC CAM AND CAUSES SAID COMPRESSION DIE TO BE MOVED SLIDABLY RELATIVE TO SAID FIRST HAND LEVER, TOWARD A MATING DIE. 